CN115313155A - Multi-junction vertical cavity surface emitting laser of heterogeneous tunnel junction and preparation method thereof - Google Patents

Abstract

The invention discloses a multi-junction vertical cavity surface emitting laser of a heterogeneous tunnel junction and a preparation method thereof, relates to the field of semiconductor lasers, and solves the problems of low power density, low quantum efficiency and low tilt efficiency and high absorption loss of the conventional vertical cavity surface emitting laser.

Description

A multi-junction vertical cavity surface emitting laser with heterogeneous tunnel junction and its preparation method

technical field

The invention relates to the field of semiconductor lasers, in particular to a heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser.

Background technique

Vertical cavity surface emitting lasers (VCSEL) have unique advantages such as small size, small divergence angle, high beam quality, low cost, and easy two-dimensional integration. Rapidly expanding on the Internet, including: 3D facial recognition, laser medical beauty, gas detection, smart home, laser radar and other applications.

The current mainstream VCSEL chip mainly adopts a single active area large aperture (5-10μm) structure, which increases the difficulty of optical design and reduces the optical power density, making it difficult to meet the requirements of high integration and high power density. Connecting multiple active regions through highly doped tunnel junctions is currently an effective way to increase power density, quantum efficiency, and slope efficiency. However, in multi-junction VCSELs, higher tunneling probability is contradictory to reducing absorption losses introduced by tunnel junctions. Although the selection of wide bandgap materials and the reduction of doping concentration are beneficial to reduce the internal loss introduced by the tunnel junction, it will also affect the tunneling probability of the tunnel junction, resulting in an increase in the voltage drop and resistance introduced by the tunnel junction. In severe cases, it will cause no tunneling effect. Conversely, if you only pursue a high tunneling probability and choose a narrow bandgap material, the absorption loss of the tunnel junction will be very large, which will also affect the characteristics of the VCSEL laser in all aspects, and make it difficult for the laser to achieve fundamental mode lasing.

Aiming at the above problems, the present invention designs a high-performance multi-junction vertical cavity surface-emitting laser based on type II heterogeneous tunnel junctions.

Contents of the invention

The object of the present invention is to provide a multi-junction vertical cavity surface emitting laser with a heterogeneous tunnel junction in order to solve the problems of low power density, quantum efficiency and slope efficiency, and high absorption loss of the existing vertical cavity surface emitting laser and its preparation method, while ensuring a lower laser threshold and high power, it reduces the series resistance and the absorption between the valence bands at the tunnel junction, and the resistance is about 40% smaller than that of the homogeneous tunnel junction, realizing providing a high Performance of multi-junction vertical-cavity surface-emitting lasers.

The present invention specifically adopts the following technical solutions in order to achieve the above object:

A multi-junction vertical cavity surface-emitting laser with a heterogeneous tunnel junction, the laser includes a P electrode, a P-type Bragg mirror group, a first oxide layer, a first active region, and a type II heterogeneous tunnel in sequence from top to bottom A junction, a second oxide layer, a second active region, an N-type Bragg mirror group, a substrate, and an N electrode.

Optionally, the type II heterogeneous tunnel junction includes: adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped Al _x Ga _1-x As, in phase The two sides of adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped Al _x Ga _1-x As are respectively p-type lightly doped Al _x Ga _1-x As And n-type lightly doped Al _x Ga _1-x As.

Optionally, the variation range of the AlxGa1 _{- xAs} composition of the p-type lightly doped and n-type lightly doped AlxGa1 _{- xAs} is: x=0.2-0.4.

Optionally, the variation range of the Al _x Ga _1-x As _y Sb _1-y composition of the p-type heavily doped Al _x Ga _1-x As _y Sb _1-y is: x=0-0.2, y=0.8-1.

Optionally, the variation range of the AlxGa1 _{- xAs} composition of the n-type heavily doped AlxGa1 _{- xAs} is: x=0-0.1.

Optionally, the p-type lightly doped and n-type lightly doped Al _x Ga _1-x As doping concentration ranges from 5×10 ¹⁷ cm ^-3 to 2×10 ¹⁸ cm ^-3 , and the thickness is 20-100nm .

Optionally, the doping concentration of the p-type heavily doped Al _x Ga _1-x As _y Sb _1-y ranges from 5×10 ¹⁹ cm ^-3 to 1×10 ²⁰ cm ^-3 , and the thickness is 5- 10nm.

Optionally, the doping concentration of the n-type heavily doped AlxGa1 _{- xAs} ranges from 8×10 ¹⁸ cm ^-3 to 3×10 ¹⁹ cm ^-3 , and the thickness is 10-20 nm.

The present invention also provides a method for preparing a heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser, comprising the following steps:

S1. Epitaxial N-type Bragg mirror group, second active region, second oxide layer, II-type heterogeneous tunnel junction, first active region, first oxide layer, and P-type Bragg mirror group on the substrate in sequence , get the first prefab;

S2. Fabricate a P electrode on the side of the P-type Bragg mirror group of the first preform away from the first active region, and fabricate an N electrode on the side of the substrate away from the N-type Bragg mirror group, Get the target laser.

Compared with the prior art, the present invention has the advantages of:

1. A heterogeneous tunnel junction vertical cavity surface emitting laser and its preparation method involved in the present invention, by introducing a heterogeneous tunnel junction into the laser, while ensuring a lower laser threshold and high power, the series resistance is reduced and the absorption between the valence bands at the tunnel junction, so that the resistance of the tunnel junction of the present invention is about 40% smaller than that of the homogeneous tunnel junction, and a high-performance multi-junction vertical cavity surface emitting laser is realized, which solves the problem of the existing vertical cavity surface emitting laser Problems with low power density, quantum efficiency and slope efficiency, and high absorption losses.

Description of drawings

Fig. 1 is a schematic structural diagram of a heterogeneous tunnel junction vertical cavity surface emitting laser.

Fig. 2 is a schematic diagram of the tunnel junction energy band structure of a heterogeneous tunnel junction vertical cavity surface emitting laser.

FIG. 3 is a schematic diagram of optical and electrical performance testing in Experiment 1.

Reference signs: 1-P electrode, 2-P-type Bragg mirror group, 3-first oxide layer, 4-first active region, 5-II-type heterogeneous tunnel junction, 6-second oxide layer, 7 -Second active region, 8-N-type Bragg mirror group, 9-substrate, 10-N electrodes

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. the embodiment.

Accordingly, the following detailed description of the embodiments of the invention provided is not intended to limit the scope of the claimed invention, but represents only selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Detailed ways

Referring to Fig. 1, a multi-junction vertical cavity surface-emitting laser with a heterogeneous tunnel junction, the laser is sequentially composed of a P electrode 1, a P-type Bragg mirror group 2, a first oxide layer 3, and a first Active region 4 , type II heterogeneous tunnel junction 5 , second oxide layer 6 , second active region 7 , N-type Bragg mirror group 8 , substrate 9 , and N electrode 10 .

It can be understood that, for a heterogeneous tunnel junction vertical cavity surface emitting laser involved in the present invention, by introducing a type II heterogeneous tunnel junction 5 into the laser, it ensures a lower laser threshold and high power while reducing the series The resistance and the absorption between the valence bands at the tunnel junction make the resistance of the type II heterogeneous tunnel junction 5 of the present invention about 40% smaller than that of the homogeneous tunnel junction, realizing a high-performance multi-junction vertical cavity surface emitting laser and solving the current problem There are problems of low power density, quantum efficiency and slope efficiency, and high absorption loss of vertical cavity surface emitting lasers.

It should be understood that in a tunnel junction, on the one hand, in order to avoid light absorption, the tunnel junction material must be composed of a semiconductor with a band gap larger than the energy of the laser wavelength; Therefore, it is difficult to achieve low resistance and low light absorption at the same time.

Traditional near-infrared multi-junction vertical cavity surface emitting lasers (such as 905, 940 and 980nm) tunnel junction materials generally use GaAs homojunction. However, for a 905nm multi-junction vertical cavity surface emitting laser, the fluorescence peak of the active region material is around 890nm at room temperature, and the corresponding photon energy is 1.393eV, while the intrinsic GaAs material has a forbidden band width of 1.424eV at room temperature. The difference between them is only 31meV. Considering the bandgap shrinkage caused by heavy doping band tail effect and carrier shielding effect, and the intrinsic absorption edge redshift caused by the electric Franz-Keldish effect, the GaAs homojunction has intrinsic properties for photons in this band. possibility of absorption. Therefore, the tunnel junction of the heterojunction is more advantageous.

E_geff≡E_gp-ΔE_c＝E_gn-ΔE_v(1)在公式(1)中，E_gp和E_gn表示p侧半导体和n侧半导体的带隙能，E_geff表示异质界面p侧的价带边和n侧的导带边之间的能隙。由于E_geff小于E_gp和E_gn，Ⅱ型异质隧道结的隧穿概率远大于同质结或Ⅰ型隧道结。Specifically, refer to the type II junction tunneling probability formula:

E _geff ≡E _gp -ΔE _c ＝E _gn -ΔE _v (1) In formula (1), E _gp and E _gn represent the band gap energy of p-side semiconductor and n-side semiconductor, and E _geff represents the p-side of heterointerface The energy gap between the valence band edge on the n side and the conduction band edge on the n side. Since E _geff is smaller than E _gp and E _gn , the tunneling probability of type II heterojunction is much higher than that of homojunction or type I tunnel junction.

Furthermore, in type II tunnel junction materials, since E _gp and E _gn are greater than the energy of the laser wavelength, and E _geff is less than the energy of the laser wavelength, light absorption can occur near the heterojunction. However, the transition from the valence band edge on the p-side of the heterointerface to the conduction band edge on the n-side requires the carrier function to penetrate the band gap, so its penetration probability is not high. In addition, in the vertical cavity surface emitting laser, the type II heterostructure tunnel junction is generally placed at the standing wave node, so the light absorption of the type II heterostructure tunnel junction is very small, and this setting ensures a lower laser threshold and high power At the same time, the resistance of the type II heterogeneous tunnel junction is about 40% smaller than that of the homogeneous tunnel junction, which greatly reduces the resistance of the vertical cavity surface emitting laser.

Furthermore, in the multi-junction vertical cavity surface-emitting laser with heterogeneous tunnel junctions involved in the present invention, an oxide layer is provided on the p-region side of each active region, and the function of the oxide layer is to limit the aperture of the light-emitting region. In addition, it can effectively suppress the leakage of electrons and further improve the quantum efficiency of the device.

The type II heterogeneous tunnel junction in the present invention includes: adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped Al _x Ga _1-x As, phase The two sides of adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped Al _x Ga _1-x As are respectively p-type lightly doped Al _x Ga _1-x As And n-type lightly doped Al _x Ga _1-x As. It should be noted that two materials, Al _x Ga _{1- x} As _y Sb _1-y and Al _x Ga _1-x As, are introduced into the tunnel junction, so that the tunnel junction has a heterogeneous structure, and the light absorption here is very small. Therefore, a lower laser threshold, a smaller resistance, and a larger output power can be realized here, and the photoelectric performance is superior.

In some embodiments of the present invention, the Al _x Ga _1-x As composition range of the aforementioned lightly p-type doped and lightly n-doped Al _x Ga _1-x As is: x=0.2-0.4.

Wherein, the change range of AlxGa1 _{- xAs} composition of above-mentioned lightly p-type doped and lightly n-doped AlxGa1 _{- xAs} is preferably x=0.3.

In some embodiments of the present invention, the Al _x Ga _1-x As _y Sb _1-y composition range of the aforementioned p-type heavily doped Al _x Ga _1-x As _y Sb _1-y is: x= 0-0.2, y=0.8-1.

Wherein, the change range of AlxGa1 _- xAsySb1 _{-y composition} of the above-mentioned p-type heavily doped _{AlxGa1 -} xAsySb1 _{- y} is preferably _x =0.1, y=0.9.

In some embodiments of the present invention, the Al _x Ga _1-x As composition of the above n-type heavily doped Al _x Ga _1- x As varies in the range: x=0-0.1.

Wherein, the variation range of the AlxGa1 _{- xAs} composition of the above-mentioned n-type heavily doped AlxGa1 _{- xAs} is preferably x=0.05.

In some embodiments of the present invention, the above-mentioned lightly doped p-type and lightly n-doped Al _x Ga _1-x As doping concentrations range from 5×10 ¹⁷ cm ^-3 to 2×10 ¹⁸ cm ^-3 , The thickness is 20-100nm.

Wherein, the aforementioned p-type lightly doped and n-type lightly doped Al _x Ga _1-x As doping concentrations range from 1×10 ¹⁸ cm ^-3 , and the thickness is 60 nm.

In some embodiments of the present invention, the above-mentioned p-type heavily doped Al _x Ga _1-x As _y Sb _1-y has a doping concentration ranging from 5×10 ¹⁹ cm ^-3 to 1×10 ²⁰ cm ^-3 , with a thickness of 5-10nm.

Wherein, the above-mentioned p-type heavily doped Al _x Ga _1-x As _y Sb _1-y preferably has a doping concentration range of 1×10 ²⁰ cm ^-3 and a thickness of 8 nm.

In some embodiments of the present invention, the above-mentioned n-type heavily doped Al _x Ga _1-x As has a doping concentration ranging from 8×10 ¹⁸ cm ^-3 to 3×10 ¹⁹ cm ^-3 , and a thickness of 10-20 nm. .

Among them, the doping concentration range of the above-mentioned n-type heavily doped Al _x Ga _1-x As is preferably 8×10 ¹⁸ , 1×10 ¹⁹ , 3×10 ¹⁹ cm ^-3 , and the thickness is 10, 12, 15, 20 nm .

The present invention also provides a method for preparing a heterogeneous tunnel junction vertical cavity surface emitting laser, comprising the following steps:

S1. Epitaxial N-type Bragg mirror group 8, second active region 7, second oxide layer 6, type II heterogeneous tunnel junction 5, first active region 4, and first oxide layer 3 on substrate 9 in sequence , P-type Bragg mirror group 2, to obtain the first preform;

S2. Fabricate a P electrode 1 on the side of the P-type Bragg mirror group 2 of the first preform far away from the first active region 4, and make a P electrode 1 on the side of the substrate 9 far away from the N-type Bragg mirror group 8. The N electrode 10 is fabricated on the side to obtain the target laser.

A GaAs substrate is preferred in the present invention.

The P electrode 1 and the N electrode 10 of the present invention are any one of gold, copper, graphite, silver or tin.

It should be noted that in the specific epitaxial process, in the already involved P-type Bragg mirror group 2, the first oxide layer 3, the first active region 4, the type II heterogeneous tunnel junction 5, and the second oxide layer 6 , the second active region 7, the N-type Bragg mirror group 8 and other layers also have a buffer layer, and the parameters are adjusted according to actual preparation requirements to carry out epitaxy on each buffer layer to meet actual requirements.

In some embodiments of the present invention, metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) can be selected as the epitaxy method to epitaxy each layer.

Example 1

A multi-junction vertical cavity surface-emitting laser with a heterogeneous tunnel junction, the laser includes a P electrode, a P-type Bragg mirror group, a first oxide layer, a first active region, and a type II heterogeneous tunnel in sequence from top to bottom A junction, a second oxide layer, a second active region, an N-type Bragg mirror group, a substrate, and an N electrode.

In this embodiment, the type II heterogeneous tunnel junction includes: adjacent p-type heavily doped Al _0.15 Ga _0.85 As _0.95 Sb _0.05 and n-type heavily doped Al _0.1 Ga _0.9 As, adjacent p-type heavily The two sides of doped Al _0.15 Ga _0.85 As _0.95 Sb _0.05 and n-type heavily doped Al _0.1 Ga _0.9 As are respectively p-type lightly doped Al _0.3 Ga _0.7 As and n-type lightly doped Al _0.2 Ga _0.7 As.

Among them, the doping concentration range of p-type lightly doped Al _0.3 Ga _0.7 As and n-type lightly doped Al _0.2 Ga _0.7 As is 5×10 ¹⁷ cm ^-3 , and the thickness is 20nm; p-type heavily doped Al _0.15 Ga The doping concentration range of _0.85 As _0.95 Sb _0.05 is 5×10 ¹⁹ cm ^-3 and the thickness is 6nm; the doping concentration range of n-type heavily doped Al _0.1 Ga _0.9 As is 8×10 ¹⁸ cm ^-3 and the thickness is 11nm .

Example 2

A multi-junction vertical cavity surface-emitting laser with a heterogeneous tunnel junction, the laser includes a P electrode, a P-type Bragg mirror group, a first oxide layer, a first active region, and a type II heterogeneous tunnel in sequence from top to bottom A junction, a second oxide layer, a second active region, an N-type Bragg mirror group, a substrate, and an N electrode.

In this embodiment, the type II heterogeneous tunnel junction includes: adjacent p-type heavily doped Al _0.2 Ga _0.8 As _0.9 Sb _0.1 and n-type heavily doped Al _0.1 Ga _0.9 As, adjacent p-type heavily doped The two sides of doped Al _0.15 Ga _0.85 As _0.95 Sb _0.05 and n-type heavily doped Al _0.1 Ga _0.9 As are respectively p-type lightly doped Al _0.2 Ga _0.8 As and n-type lightly doped Al _0.2 Ga _0.8 As.

Among them, p-type lightly doped Al _0.2 Ga _0.8 As and n-type lightly doped Al _0.2 Ga _0.8 As have a doping concentration range of 1×10 ¹⁸ cm ^-3 and a thickness of 60nm; p-type heavily doped Al _0.2 Ga _0.8 The doping concentration range of As _0.9 Sb _0.1 is 0.5×10 ²⁰ cm ^-3 and the thickness is 8nm; and the doping concentration range of n-type heavily doped Al _0.1 Ga _0.9 As is 2×10 ¹⁹ cm ^-3 and the thickness is 15nm .

Example 3

A multi-junction vertical cavity surface-emitting laser with a heterogeneous tunnel junction, the laser includes a P electrode, a P-type Bragg mirror group, a first oxide layer, a first active region, and a type II heterogeneous tunnel in sequence from top to bottom A junction, a second oxide layer, a second active region, an N-type Bragg mirror group, a substrate, and an N electrode.

In this embodiment, the type II heterogeneous tunnel junction includes: adjacent p-type heavily doped Al _0.15 Ga _0.85 As _0.95 Sb _0.05 and n-type heavily doped Al _0.1 Ga _0.9 As, adjacent p-type heavily The two sides of doped Al _0.2 Ga _0.8 As _0.9 Sb _0.1 and n-type heavily doped Al _0.1 Ga _0.9 As are respectively p-type lightly doped Al _0.2 Ga _0.8 As and n-type lightly doped Al _0.2 Ga _0.8 As.

Among them, p-type lightly doped Al _0.2 Ga _0.8 As and n-type lightly doped Al _0.2 Ga _0.8 As have a doping concentration range of 2×10 ¹⁸ cm ^-3 and a thickness of 100nm; p-type heavily doped Al _0.15 Ga _0.85 The doping concentration range of As _0.95 Sb _0.05 is 1×10 ²⁰ cm ^-3 and the thickness is 10nm; and the doping concentration range of n-type heavily doped Al _0.1 Ga _0.9 As is 3×10 ¹⁹ cm ^-3 and the thickness is 20nm .

Furthermore, in order to verify the optical and electrical properties of the laser emitting device of the present invention, the following test examples were carried out.

Test example. Check the optical and electrical performance of the emitting laser

1.1 Experimental design

Two treatment groups were set up in the experiment, the experimental group was the triple-junction vertical cavity surface-emitting laser of the Al _0.1 Ga _0.9 As/Al _0.15 Ga _0.85 As _0.95 Sb _0.05 type II heterogeneous tunnel junction involved in Example 1, and the control group was the Ordinary homogeneous tunnel junction vertical cavity surface emitting lasers are tested for their optical and electrical performance under the same test conditions.

The test results are shown in Figure 3, where the dotted line represents the control group (vertical cavity surface emitting laser with ordinary GaAs homogeneous tunnel junction), and the solid line represents the experimental group (Al _0.1 Ga _0.9 As/Al _0.15 Ga _0.85 As _0.95 Sb _0.05 Ⅱ type hetero-tunnel junction vertical-cavity surface-emitting laser).

After the inspection, the current-power curve representing the optical performance and the current-voltage curve representing the electrical performance are obtained respectively.

1.2 Analysis of results

Referring to the current-power curve in Figure 3, it can be seen that in terms of optical performance, the current lasing threshold of the experimental group is 1.1mA, while the current lasing threshold of the control group is 1.2mA. It can be seen that the current lasing threshold of the two is not much different , this is because the use of type II heterogeneous tunnel junction Al _x Ga _1-x As/Al _x Ga _1-x As _y Sb _1-y does not increase the absorption loss. It can be seen that compared with the control group, when the lasing threshold is kept constant, the differential resistance and slope efficiency of the experimental group are better. Therefore, the heterogeneous tunnel junction vertical cavity surface emitting laser of Example 1 has a higher photoelectric conversion efficiency.

Referring to the current-voltage curve, in terms of electrical properties, the curve of the experimental group is steeper, that is, the differential resistance of the experimental group is smaller than that of the control group. It can be seen that the type II tunnel junction Al _x Ga _1-x As/Al _x Ga _1-x As _y Sb _1-y has a shorter tunneling distance, which increases the tunneling probability of electrons, thereby reducing the differential resistance.

Combining the two sets of curves, compared with the control group, when the lasing threshold is kept constant, the experimental group has better differential resistance and slope efficiency, and has higher photoelectric conversion efficiency.

In summary, a heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser involved in the present invention, by introducing a heterogeneous tunnel junction into the laser, ensures a lower laser threshold and high power while reducing the The series resistance and the absorption between the valence bands at the tunnel junction make the resistance of the tunnel junction of the present invention about 40% smaller than that of the homogeneous tunnel junction, realizing a high-performance multi-junction vertical cavity surface emitting laser and solving the problem of existing vertical cavity surface emitting lasers. Issues of low power density, quantum efficiency, and slope efficiency of emitting lasers, and high absorption losses.

The above embodiment is only one implementation mode of the present invention, and its description is relatively specific and detailed, but it should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (9)

1. A multi-junction vertical cavity surface-emitting laser of a heterogeneous tunnel junction, characterized in that: the laser is sequentially composed of a P electrode, a P-type Bragg mirror group, a first oxide layer, and a first active region from top to bottom , Type II heterogeneous tunnel junction, a second oxide layer, a second active region, an N-type Bragg mirror group, a substrate, and an N electrode. 2. A heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser according to claim 1, characterized in that: the type II heterogeneous tunnel junction comprises: adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped Al _x Ga _1-x As, adjacent p-type heavily doped Al _x Ga _1-x As _y Sb _1-y and n-type heavily doped The two sides of Al _x Ga _1-x As are p-type lightly doped Al _x Ga _1-x As and n-type lightly doped Al _x Ga _1-x As respectively. 3. The multi-junction vertical cavity surface-emitting laser of a heterogeneous tunnel junction according to claim 2, wherein the p-type lightly doped and n-type lightly doped Al _x Ga _1-x As Al _x Ga _1-x As composition range is: x = 0.2-0.4. 4. The multi-junction vertical cavity surface emitting laser of a heterogeneous tunnel junction according to claim 2, wherein the p-type heavily doped Al _x Ga _1-x As _y Sb _1-y Al _x Ga _1-x As _y Sb _1-y composition ranges: x=0-0.2, y=0.8-1. 5. The multi-junction vertical cavity surface-emitting laser of a heterogeneous tunnel junction according to claim 2, wherein the Al _x Ga 1-x of the n-type heavily doped Al _x Ga _{1-x As} The variation range of As composition is: x=0-0.1. 6. The multi-junction vertical cavity surface emitting laser of a heterogeneous tunnel junction according to claim 3, characterized in that: the p-type lightly doped and n-type lightly doped Al _x Ga _1-x As doped The concentration range is 5×10 ¹⁷ cm ^-3 -2×10 ¹⁸ cm ^-3 , and the thickness is 20-100nm. 7. The multi-junction vertical cavity surface emitting laser of a heterogeneous tunnel junction according to claim 4, characterized in that: the doped p-type heavily doped Al _x Ga _1-x As _y Sb _1-y The impurity concentration ranges from 5×10 ¹⁹ cm ^-3 to 1×10 ²⁰ cm ^-3 , and the thickness is 5-10nm. 8. A heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser according to claim 5, characterized in that: the doping concentration range of the n-type heavily doped AlxGa1 _{- xAs} is 8× 10 ¹⁸ cm ^-3 —3×10 ¹⁹ cm ^-3 , with a thickness of 10-20nm. 9. The method for preparing a heterogeneous tunnel junction multi-junction vertical cavity surface emitting laser according to any one of claims 1 to 8, characterized in that it comprises the following steps: S1. Epitaxial N-type Bragg mirror group, second active region, second oxide layer, II-type heterogeneous tunnel junction, first active region, first oxide layer, and P-type Bragg mirror group on the substrate in sequence , get the first prefab; S2. Fabricate a P electrode on the side of the P-type Bragg mirror group of the first preform away from the first active region, and fabricate an N electrode on the side of the substrate away from the N-type Bragg mirror group, Get the target laser.

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